The South Korean government said Friday it would resume radiation testing for defectors from near North Korea’s nuclear test site in Punggye-ri to check for possible exposure.

Lee Hyo-jung, the Ministry of Unification’s deputy spokesperson, said in a briefing that from this year testing will be offered to North Koreans who lived in Kilju or nearby regions after North Korea’s first nuclear test in 2006, if they are willing. There are 881 defectors who would be eligible for the testing in the country, she said.

“The ministry had tested some defectors from around the area before, but it was done with such a small sample size. For more meaningful results, the ministry plans on conducting the tests on a larger scale starting this year, with the consent of the defectors,” she said.

The tests are meant to determine if the defectors have been exposed to radiation generated by the nuclear weapons tests, and how their health may have been affected as a result, she added.

In 2017 and 2018, the ministry, together with the Korea Institute of Radiological Medical Sciences, carried out radiation tests for 40 defectors from and around Kilju and found worrying levels of chromosomal abnormalities in nine of them. The ministry was then criticized for not disclosing the full results to the public.

The ministry’s announcement follows Tuesday’s report by the Transitional Justice Working Group, a Seoul-based nongovernmental organization tracking human rights abuses. In the report, the group said hundreds of thousands of North Koreans lived in the potentially affected vicinity of Punggye-ri, putting them at risk of exposure to radioactive leaks or contamination.

The group called on the South Korean government to investigate the risk and the possible extent of radiation exposure for North Korean defectors who had lived near the nuclear test site, as well as provide necessary medical support.